This invention relates to a method and apparatus for the chemical analysis of matter. In one aspect, it relates to the determination of the quantity of volatile hydrocarbons and the hydrocarbon generating potential of the insoluble organic material or kerogen present in a geological sample. The invention relates in another aspect to an injection system for a gas chromatograph or other analytical instrument.
In the field of geochemical research and petroleum exploration, an area of growing interest is the analysis of geological samples to determine the remaining petroleum-generating potential of these samples. Work in this field has been directed to methods for removing hydrocarbons from geological samples and analyzing the hydrocarbons, to apparatus for laboratory and field analysis of geological samples, and to the development of theoretical and practical models that allow the raw data obtained to be used for purposes of petroleum exploration. A method known in the art for such analyses involves the thermal extraction of volatile hydrocarbons from a kerogen (insoluble organic portion of a sedimentary rock) or rock sample followed by pyrolysis of the remaining organic material. Conventional methods such as flame ionization detection can be used to determine the quantity of hydrocarbons generated in each operation, and the information thus obtained can be used to determine certain petroleum exploration-related characteristics of the sample.
A pyrolysis unit, or modified gas chromatograph, is used for such thermal analytical methods. A rock sample is placed in a sample inlet which has been heated to the temperature of hydrocarbon volatilization. The sample is subsequently heated to a higher temperature, generally by means of a radiant heater, to pyrolyze the remaining organic matter. A gas detection device such as a flame ionization detector responds to the quantity of hydrocarbons generated and a recorder instrument records graphically the detector response versus time. The detector responses obtained are compared with standards developed to determine the actual quantities of hydrocarbons generated, and to thus assess the petroleum potential of the sample.
In performing analyses of the type described above, it is desirable to be able to make accurate, reproducible determinations of the quantity of volatile hydrocarbons present in the geological sample. It is also desirable, both for economic reasons and for performing rock sample analyses in the field, to have analytical equipment which is simple and compact.
It is therefore an object of the invention to provide an improved apparatus for thermal analysis of solids and liquids.
It is a further object of the invention to enable more accurate determination of the remaining hydrocarbon generating potential of the insoluble organic matter.